1. Field of the Invention
The invention relates to a projection wall for open-air cinemas.
2. Description of the Prior Art
In recent years open-air cinema has become increasingly popular. Especially during film festivals and summer night presentations a large audience is watching films outdoors. This requires large out-door screens. Such screens should be easy to install but still be weather- and storm-proof.
For this purpose it is e.g. possible to use a conventional screen mounted to a scaffolding erected for this purpose. Such a scaffolding must, however, be solid enough to weather even strong storms. This is very difficult since enormous wind pressures can arise when using large screens with a surface of several hundred square meters.
Therefore it is preferred to use a solution where the screen can be lowered. This can be achieved by attaching the screen to a frame and by pivotally anchoring the lower end of the frame in the ground. The screen can be brought into its upright position by ropes, which are attached to its upper end and guided through the upper part of the scaffolding or suitable support columns. This construction leads to problems because the ropes can only exert pulling but no pushing forces. If the screen is to be lowered, a strong wind pressing against the surface of the screen and acting against the desired tilting motion can make the pivoting very difficult if not impossible.
Furthermore, the known solutions require strong anchorings or a heavy ballast for the scaffolding or support columns to secure these structures from being blown over in a storm.